I may have expected any fault with RAM to impact on other browsers and processes not just Firefox.

There are free utilities to test RAM, install and run such a utility (overnight maybe) and see if problems are discovered.

• One example https://wikipedia.org/wiki/Memtest86

Start Firefox in Safe Mode {web Link} by holding down the <Shift (Mac Options) > key, and then starting Firefox. Is the problem still there?

It is possible that your security software (firewall, anti-virus) blocks or restricts Firefox or the plugin-container process without informing you, possibly after detecting changes (update) to the Firefox program.

Remove all rules for Firefox and the plugin-container from the permissions list in the firewall and let your firewall ask again for permission to get full, unrestricted, access to install for Firefox and the plugin-container process and the updater process.

See:

• https://support.mozilla.org/kb/Server+not+found
• https://support.mozilla.org/kb/Firewalls

• https://support.mozilla.org/kb/fix-problems-connecting-websites-after-updating

FredMcD said

Start Firefox in Safe Mode {web Link} by holding down the <Shift (Mac Options) > key, and then starting Firefox. Is the problem still there?

Firefox still not opening.

FredMcD said

Start Firefox in Safe Mode {web Link} by holding down the <Shift (Mac Options) > key, and then starting Firefox. Is the problem still there?

Firefox is not opening at all to open it in safe mode.

Start your Computer in safe mode. Then start Firefox. Try Safe web sites.

Starting The Computer In Safe Mode;
Free Online Encyclopedia

John99 said

I may have expected any fault with RAM to impact on other browsers and processes not just Firefox. There are free utilities to test RAM, install and run such a utility (overnight maybe) and see if problems are discovered.

• One example https://wikipedia.org/wiki/Memtest86

No issue with other browsers, only with firefox. I have not seen any

FredMcD said

Start your Computer in safe mode. Then start Firefox. Try Safe web sites. Starting The Computer In Safe Mode;
Free Online Encyclopedia

I am able to use firefox in safe mode. But what i need to do next.

Sampath said

Recently, I have upgraded my PC's RAM. I observed that firefox is crashing frequently after my RAM upgrade. So, I have done clean uninstall. After that I installed firefox, still observing the same. So, repeatedly I have followed this procedure. After few installations, firefox is not loading at all. I have opened task manager and seen the firefox process. It will appear there for few seconds and then disappear from there (task manager). I don't know what to do. I am using chrome against my liking to firefox from around a month. Please help me to resolve this issue.

I have refreshed firefox in safe mode

https://support.mozilla.org/en-US/kb/refresh-firefox-reset-add-ons-and-settings

And then found an application blocking firefox usage by trail in safe mode. I changed the settings of that application and it resolved the issue.

I am glad Fred's suggestion helps, but that is just a troubleshooting step. If Firefox will not start even in its own safemode, but does in Windows Safe Mode your problem could be some process Windows is starting up.

This article explains Windows SafeMode and the next troubleshooting steps

• http://windows.microsoft.com/en-gb/windows/what-is-safe-mode

You probably have not yet tried the steps suggested upthread by cor-el

Great! Looks like you solved it. Our posts crossed.

• What was the application that you needed to change settings for ?

John99 said

Great! Looks like you solved it. Our posts crossed.

• What was the application that you needed to change settings for ?

Mine is Enterprise Laptop with EMET (Enhanced Mitigation Experience Toolkit) Agent running as windows 7 background process. After my RAM upgrade there is a silent upgrade of this software which has restricted the firefox process memory etc. access. This caused my firefox not to start. So figured the culprit program in windows safe mode. I have done corresponding changes to the setting of this application.